Method and means for breaking the spiral ended wood flakes produced while cutting a flat surface on wood



Apnl 12, 1966 D. JOHNSON 3,245,442

METHOD AND MEANS FOR BREAKING THE SPIRAL ENDED WOOD FLAKES PRODUCED WHILE CUTTING A FLAT SURFACE ON WOOD Filed Feb. 10, 1964 2 Sheets-Sheet l FIG l5 INVENTOR. DONALD L JOHNSON ATTORNEY Apnl 12, 1966 D. L. JOHNSON 3,245,442

METHOD AND MEANS FOR BREAKING THE SPIRAL ENDED WOOD FLAKES PRODUCED WHILE CUTTING A FLAT SURFACE ON WOOD Filed Feb. 10, 1964 2 Sheets-Sheet 2 INVEN TOR. DONALD L. JOHNSON ATTOR NEY United States Patent METHOD AND MEANS FDR BREAKING THE SPIRAL ENDED WOOD FLAKES PRODUCED WHILE CUTTING A FLAT SURFACE 0N Donald L. Johnson, 1340 Heatherwood W., Tacoma, Wash. Filed Feb. 10, 1964, Ser. No. 343,832 7 Claims. (Cl. 144-176) The present invention is concerned with the wood flakes produced by rotary cutters of the type described in my United States Letters Patent No. 2,889,859, issued June 9, 1959; No. 2,949,946, issued August 23, 1960; No. 2,964,079, issued December 13, 1960, and in my pending applications Serial No. 279,411, filed May 10, 1963, entitled Apparatus for Flaking and Surfacing Wood, and Serial No. 329,665, filed December 11, 1963, entitled Method and Means for Obtaining Smooth Wood Flakes While Producing a Flat Surface on Wood.

Such rotary cutters have wood slicing knives with substantially radially-extending cutting edges arranged in a helical-spiral, radially-retreating, axially-advancing cutting path so that the rotary cutter or cutterhead will produce a flat surface on Wood when the wood is moved in a direction perpendicular to the axis of rotation of the cutterhead at a speed properly synchronized with the rotational speed of the cutterhead. The cutting or slicing action, which takes place within the axial and radial cutting range of the cutterhead, results in precisely cut wood flakes being produced. These flakes, which are sliced across the grain of the wood, are spiral ended, their cut ends corresponding to the curvature of the spiral path of the cutting knives and their width generally corresponding to the full width of the cut surface of the wood. Thus their width, measured in a direction per endicular to the grain of the wood, is usually several times their length.

If such flakes are not broken into smaller flakes (thus into spiral ended flakes of smaller width) they would be less satisfactory for pulping or for flakeboard use, or other purposes, and furthermore when these flakes are not broken up into smaller sizes or widths they create a bulk problem inasmuch as a unit volume then comprises relatively small amount of actual material. On the other hand heretofore the subsequent cutting of these flakes into smaller desired widths has involved labor and expense, and also, since there are naturally weak points in these flakes, if the subsequent cutting of a flake happens to occur adjacent a weak point, undesirable splinters or fines are apt to result incidentally from the cutting.

The object of the present invention is to provide practical method and means whereby these spiral ended wood flakes can be broken instead of having to be cut, into smaller widths.

A further object is to have the wood flakes, produced by such cutterheads, automatically broken into smaller widths as they are produced.

An additional specific object of the invention is to cause each flake to be broken into random widths, within a desired range of widths, and to have the breaks occurring mainly at the weak points in the flakes with the consequent advantage of keeping the strongest portion of a wood flake intact as much as possible with the breaking of the flake into the required smaller Width portions.

The manner in which these objects are attained and the various means which may be employed for such purpose will be briefly explained and described with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic view illustrating in general the operation of a rotary cutter or cutterhead of a type 3,245,442 Patented Apr. 12, 1966 described in the above mentioned prior patents and pending applications;

FIG. 2 is a plan view of a representative wood flake as sliced from the surface of the wood with the operation of such cutterhead, the flake illustrated being shown as unbroken;

FIG. 3 is a view illustrating the wood flake of FIG. 2 broken into smaller width pieces in accordance with the present invention by bending the flake laterally in one direction in the plane of the flake;

FIG. 4 is a similar view illustrating the flake broken by the bending of the flake laterally in the opposite direction in the plane of the flake;

FIG. 5 is a view illustrating such a flake broken by application of a torsional or twisting force to the flake;

FIG. 6 is a view of the upper face of a single knife bar adapted for use in a cutterhead of the type previously indicated, but provided with a special flake-thrusting ridge for the purpose of bending the flake laterally as the flake leaves the cutting edge of the knife bar, illustrating in full lines the resulting lateral bending and breaking of the flake as it moves on the knife bar and indicating in broken lines the normal course of the flake if the knife bar were not provided wtih such flake-thrusting ridge;

FIG. 7 is an end elevation of the same knife bar, taken at the rear end of the knife bar and thus on the line 7-7 of FIG. 6, but with the wood flake omitted;

FIG. 8 is a fragmentary elevational view of the working face of a cutterhead in which a pressure bar is provided for each knife bar, as described in pending application Serial No. 329,665 previously mentioned;

FIG. 9 is a fragmentary section on line 99 of FIG. 8 drawn to a considerably larger scale;

FIG. 10 is a fragmentary sectional view similar to FIG. 9, but showing a special groove for the cut flake adjacent the pressure bar in order that the forcing of the flake along this groove will result in the flake being broken up by the torsional stress applied to the flake;

FIG. 11 is a section on line 1111 of FIG. 10, drawn to a larger scale, illustrating the twisting of the flake while being forced along the special groove shown in FIG. 10;

FIG. 12 is a fragmentary sectional view similar in part to FIG. 9 but drawn to a larger scale and showing a special flake breaking member set in the slot between the knife blade and the pressure blade for the purpose of giving lateral bend and some torsional twist to the flake as the flake is forced past this partial obstruction and thereby causing breaking of the flake;

FIG. 13 is a section on line 13-13 of FIG. 12;

FIG. 14 is a view of the flake breaking member of FIGS. 12 and 13 shown by itself and removed from the cutterhead;

FIG. 15 is a bottom end view of the flake breaking member of FIGS. 12, 13, and 14, the view being taken on the line 1515 of FIG. 14;

FIG. 16 is an elevational view of a modified form of such flake breaking member;

FIG. 17 is a fragmentary sectional view similar in part to FIG. 9 but drawn to the same scale as FIG. 12 and showing the lower face of the pressure bar formed with a modified construction to cause breaking of the flake;

FIG. 18 is a view of the bottom face of the modified pressure bar of FIG. 17 by itself, the view being taken along line 1818 of FIG. 17 and showing a portion of the wood flake in the slot between the bottom face of the pressure bar and the top face of the knife bar; and

FIG. 19 is a sectional view of the pressure bar of FIGS. 17 and 18 taken on line 1919 of FIG. 18.

Referring first to FIG. 1, the rotary cutter or cutterhead 25, illustrated diagrammatically in this figure, is similar to the cutterheads described in the previously mentioned patents and pending applications in that it has a plurality of identical volute peripheral portions, with the radius of each volute portion decreasing in the direction opposite the direction of rotation of the cutterhead. Each volute portion carries an equal number of equally spaced knife bars which provide substantially radially extending cutting edges the cutting edges of the knife bars of each volute peripheral portion being arranged in a helical-spiral, axially advancing and radially retreating knife line. The cutting of the flat surface 26 on the Wood W, as the wood is moved in a direction perpendicular to the axis of rotation of the cutterhead at a speed properly synchronized with the speed of rotation of the cutterhead, results, as is well known, in the slicing of wood flakes from the wood. Such a typical wood flake 27 is illustrated in FIG. 2. Since the flakes, such as the flake 27, are sliced across the grain of the wood by knives which travel in a curved path, the ends 28 and 29 of the flake will be curved, and, unless the flake is broken, the width of the flake, measured in a direction perpendicular to the grain of the wood, will correspond to the width of the surface cut along the wood by the cutterhead.

Also, since these wood flakes are sliced across the grain of the wood, it is possible to reduce them to spiral ended flakes of desired smaller widths by breaking them with the grain which, for reasons previously mentioned, is preferable to the cutting of the flakes into shorter widths. Such breaking of the flakes may be accomplished either by bending the flakes laterally, by subjecting them to torsional twist, or by a combination of lateral bending and torsional twisting.

In FIG. 3 the flake 27 is illustrated as being broken into smaller width sections as the result of lateral bending in the plane of the flake in one direction; while FIG. 4 illustrates how the same flake may be broken similarly by lateral bending in the opposite direction. Further FIG. illustrates how the flake may be broken by torsional twist. In each case the breaks 30 in the flake will most likely occur at the weakest .points in the flakes.

As each flake is sliced from the wood by the cutting edge of a knife it will ordinarily be thrust along the face of the knife bar and then discharged from the rotating cutterhead. In the carrying out of the present invention the rupturing of the flake in general is brought about by forcing the flake to vary from its normal course on the knife bar or in the slot between the knife bar and the associated pressure bar.

In FIG. 6 the top face of a knife bar 31 is shown which has been formed with a special ledge 32 for the purpose of engaging the inner end of the flake 33 as it moves on the knife bar and forcing it outwardly from its normal path, thus outwardly with respect to the axis of rotation of the cutterhead. This ledge 32 increases in width from the cutting edge of the knife bar to the rear end of the knife bar. With the rapid rotation of the cutterhead and the rapid relative movement of the flake with respect to the knife bar, the resulting lateral bending thrust, forcing the flake outwardly from its normal course, results in the breaking of the flake as indicated in FIG. 6 and as illustrated in FIG. 3. This illustrates one means by which the present invention may be carried out. While the knife bar '31 of FIGS. 6 and 7 is formed with only a single cutting knife blade similar means may be employed with knife bars having two or more cutting blades, such as the knife bars described in pending application Serial No. 279,411, in which case a special ledge, such as the ledge 32, would be provided on the top face of the knife bar for each blade of the knife bar.

FIGS. 8, 9 and show a knife bar 34 and cooperating pressure bar 35 in a cutterhead 36 as described in pending application Serial No. 329,665, except that in FIG. 10 there is shown a special groove 37 in the cutterhead, in the recess between the knife bar and the cooperating pressure bar, which extends along adjacent the lower face of the pressure bar. This special groove 37 (see also FIG. 11) is provided for the purpose of engaging the inner end of the flake as it moves from the cutting edge of the knife along the recess in the cutterhead between the knife bar and the cooperating pressure bar. With such arrangement the curved inner end of the wood flake 38 is forced to travel along in this special groove 37 and the wood flake cannot move along in what would be its normal path over the top face of the knife bar. While the inner edge of the flake is held in the groove 37 the outer curved edge of the flake seeks to move along in normal manner on the top face of the knife bar 34. As a result a torsional twist is imposed on the flake as illustrated in part in FIG. 11. Due to the fact that the recess in the cutterhead between the pressure bar and the knife bar increases in width from the working face to the rear face of the cutterhead periphery, this twisting force on the flake increases as the flake is forced along in the widening recess and results in breaking the flake as illustrated in FIG. 5, and the fracturing of the flake taking place with the grain of the flake in the weakest points.

Another means which may be employed to cause the desired breaking of each flake consists in the placing of an intercepting, flake breaking member in the path of a flake as it moves along over the top face of the knife bar. FIGS. 12 and 13 show a special flake breaking member 39 set in a cavity provided in the recess 40 of the cutterhead between the knife bar 41 and the corresponding pressure bar 42. In this example the cavity for receiving the member 39 joins the slot for the knife bar 41 and the inserted or base portion of the member 39 has a flat serrated side portion 43 (FIG. 14) to correspond with the serrated wall of the knife bar slot and adjacent wall of the knife bar base. Thus, when the member 39 is set in place in its cavity and the knife bar is slid into place in the knife bar slot, the member 39 will be held firmly secured in place with only the top 44 of this member 39 extending up into the recess between the knife bar and pressure bar and thus into the path of the flake.

The top 44 of this flake breaking member 39 is substantially semi-spherical in shape and its flat side bears against the top face of a knife bar 41 as shown in FIGS. 12 and 13. Thus, as the flake is thrust along on the top face of a knife bar, the engagement of the inner end edge of the flake with this semi-spherical top portion 44 of the member 39 results in a combined lateral bending and torsional twisting of the flake as the engaged end of the flake moves around and over this obstruction. Such combined bending and twisting of the rapidly moving flake causes desired rupturing or breaking of the flake at weak spots, the breaks extending in the direction of the grain in the flake.

Instead of having the inserted base portion of the flake breaking member 39 formed as shown in FIGS. 13 and 14 the base may be cylindrical and threaded on the outside and set into a correspondingly threaded cylindrical cavity in the cutterhead recess prior to the setting of the knife bar in place. FIG. 16 shows a member 39' having such a modified base portion.

Still another means which may be employed for obtaining the desired breaking up of each break as produced is shown in FIGS. 17, 18, and 19. In FIG. 17 portions of the knife bar and corresponding pressure bar are indicated by the reference characters 45 and 46 respectively. The bottom face of the pressure bar 46 is formed with a special ridge 47 along the outer edge. This ridge starts with a beveled end portion 47 spaced a short distance from the heel of the pressure bar and knife edge of the knife bar. The width of the lower face of the pressure bar is slightly greater than the length of the out flake. As the outer cut edge or end of the flake 48 contacts the beginning of the ridge 47 the flake receives a lateral thrust, as illustrated in FIG. 18, (and also as illustrated in FIG. 4), causing rupturing of the flake and resulting in the flake being broken into widths equal approximately to the distance of the end of the ridge 47 from the cutting edge of the knife bar.

Several examples thus have been shown and briefly described of means by which the flakes may be broken into the desired smaller widths automatically as they are being sliced by the cutterhead, such breaking being produced by lateral bending, by torsional force, or by a combination of these. Obviously other specific means could be employed and provided on the knife bar or pressure bar or interposed in the cutterhead recess between the knife bar and pressure bar for the carrying out of the method comprised in the present invention. It is not intended to restrict the invention to the particular means illustrated, or to limit the invention otherwise than as the claims provide.

I claim:

1. In the production of wood flakes from a mass of wood by a rotating cutterhead of the character described by which spiral-ended flakes are formed with [a succession of identical cuts made across the grain of the wood, the method of breaking each flake into desired smaller portions as the flake is produced which consists in bending the flake laterally in the plane of the flake during its travel in the cutterhead and before being discharged from the cutterhead, whereby breaks will be developed in the flake running lengthwise with the grain in the flake.

2. In the production of wood flakes from a mass of wood by a rotating cutterhead of the character described by which spiral-ended flakes are formed with a succession of identical cuts made across the grain of the wood, the method of breaking each flake into desired smaller portions as the flake is produced which consists in subjecting the flake to a torsional twisting force during its travel in the cutterhead and before being discharged from the cutterhead, whereby breaks will be developed in the flake running lengthwise with the grain in the flake.

3. In the production of wood flakes from a mass of wood by a rotating cutterhead of the character described by which spiral-ended flakes are formed with a succession of identical cuts made across the grain of the wood, the method of breaking each flake into desired smaller portions as the flake is produced which consists in subjecting the flake to a combined torsional twisting stress and lateral bending stress during its travel in the cutterhead and before being discharged from the cutterhead, whereby breaks will be developed in the flake running lengthwise with the grain in the flake and usually at weak points in the flake.

4. In a rotating cutterhead of the character described for flaking and surfacing wood, the cutterhead having its periphery formed into a plurality of identical volute portions each having a radius decreasing constantly in the direction opposite from the direction of rotation, equally spaced knife bars mounted in the volute portions of the cutterhead periphery, said knife bars inclined forwardly in the direction of rotation of the cutterhead and extending in planes all having the same angularity with the cutterhead axis, said knife bars having substantially radially-extending cutting blade edges with said cutting edges of the knives in each of said volute portions advancing axially towards the wood in the direction opposite from the direction of rotation of the cutterhead, and a flake-directing ridge on the top face of each knife bar for forcing the wood flakes radially outwardly from their normal course on said knife bars, whereby to produce lateral bending of said flakes on said knife bars to cause breaks in said flakes running lengthwise with the wood grain in said flakes.

5. In a rotating cutterhead of the character described for flaking and surfacing wood, the cutterhead having its periphery formed into a plurality of identical volute portions each having a radius decreasing constantly in the direction opposite from the direction of rotation and the volute portions of the cutterhead having identical equallyspaced recesses on their peripheries, a knife bar and a pressure bar secured spaced apart in each recess, said pressure bars being located in advance of said knife bars respectively, and an intercepting flake-breaking member in each recess adjacent the top face of the knife bar in the recess, said intercepting members forcing the wood flakes from their normal course on said knife bars, whereby to cause breaks in said flakes.

6. In a rotating cutterhead of the character described for flaking and surfacing wood, the cutterhead having its periphery formed into a plurality of identical volute portions each having a radius decreasing constantly in the direction opposite from the direction of rotation and the volute portions of the cutterhead having identical equallyspaced recesses on their peripheries, a knife bar and a pressure bar secured spaced apart in each recess, said pressure bars being located in advance of said knife bars respectively, and each recess provided with a special flake-engaging groove extending along adjacent the lower face of the pressure bar for the entire length of the pressure bar, whereby the inner spiral ends of the flakes cut by said knife bars will be held by said grooves out of their normal course on the top faces of said knife bars so as to cause a twisting force to be exerted on the flakes in said recesses for the purpose of producing breaks in said flakes running lengthwise with the wood grain in said flakes.

7. In a rotating cutterhead of the character described for flaking and surfacing wood, the cutterhead having its periphery formed into a plurality of identical volute portions each having a radius decreasing constantly in the direction opposite from the direction of rotation and the volute portions of the cutterhead having identical equallyspaced recesses on their peripheries, a knife bar and a pressure bar secured spaced apart in each recess, said pressure bars being located in advance of said knife bars respectively, and a flake-engaging ridge on the bottom face of each pressure bar, said ridge extending along the outer edge of said bottom face of the pressure bar and beginning a spaced distance inwardly from the blade edge of the associated knife bar, whereby said ridges on said pressure bars will engage the outer cut spiral ends of the flakes as the flakes move along in said recesses beyond the blade edges of said knife and will force the flakes from their normal course in said recesses for the purpose of causing breaks in said flakes.

N 0 references cited.

WILLIAM W. DYER, IR., Primary Examiner.

R. I. ZLOTNIK, Assistant Examiner. 

1. IN THE PRODUCING OF WOOD FLAKES FROM A MASS OF WOOD BY A ROTATING CUTTERHEAD OF THE CHARACTER DESCRIBED BY WHICH SPIRAL-ENDED FLAKES ARE FORMED WITH A SUCCESSION OF IDENTICAL CUTS MADE ACROSS THE GRAIN OF THE WOOD, THE METHOD OF BREAKING EACH FLAKE INTO DESIRED SMALLER PORTIONS AS THE FLAKES IS PRODUCED WHICH CONSISTS IN BENDING 